Chromatography carrier gas
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Why is it necessary to use nitrogen as a carrier gas when analyzing syngas with a chromatograph? I would like to ask those who are experienced in this field: what is the principle behind using nitrogen as a carrier gas?
The carrier gas is like the subway, while the other sample gases are like the passengers on that subway. The carrier gas ensures that only one passenger (a type of gas) is present in each carriage, and it also isolates different gases from one another; without a carrier gas, there would be a vacuum between the various gases, and they would definitely diffuse. Nitrogen is used as the carrier gas because it is not present in your sample gas, so it does not cause any interference, and it is relatively inexpensive.
Syngas consists mainly of hydrogen and carbon monoxide, with a small amount of methane. Using nitrogen as the carrier gas allows for the simultaneous analysis of components such as hydrogen, carbon monoxide, and methane; the composition of nitrogen is generally not analyzed in syngas analysis. If hydrogen is used, it is not possible to analyze the hydrogen concentration in the sample at the same time; helium is too expensive. Argon can also be used as a carrier gas, but its thermal conductivity may pose limitations, resulting in poor analysis accuracy.
How does the carrier gas enter the chromatograph for separation? Is separation carried out based on density or other differences in properties?